Why is infrared light commonly used in photoelectric sensors?

• A. It is cheaper
• B. To minimize interference from ambient light
• C. It has higher resolution
• D. It travels faster

Answer: (B)

Infrared light is chosen for photoelectric sensors mainly to minimize interference from ambient light. Ambient lighting—sunlight and indoor lights—puts out a lot of energy in the visible spectrum, which can trigger sensors that aren’t selective. By using infrared, and often pairing it with filters and synchronized pulses, the sensor becomes selective for that wavelength and largely ignores visible light. This makes the sensor more reliable in different lighting conditions and environments, reducing false detections. Infrared is also invisible to the human eye, which helps avoid glare and distractions in the monitored area.